Vital Question: Energy, Evolution, and the Origins of Complex Life

by Nick Lane

We use about 2 milliwatts of energy per gram – or some 130 watts for an average person weighing 65 kg, a bit more than a standard 100 watt light bulb. That may not sound like a lot, but per gram it is a factor of 10,000 more than the sun (only a tiny fraction of which, at any one moment, is undergoing nuclear fusion). Life is not much like a candle; more of a rocket launcher.